ARE YOU LEFT-HANDED?

Otago Daily Times, Issue 20337, 20 February 1928, Page 14

ARE YOU LEFT-HANDED?

Left-handedness is surprisingly prevalent. Some authorities estimate it as high as 4 per cent, of the population; whatever the total, males predominate largely over females. Discussing Hie question in the December issue of the Empire Review, Dr Leonard Williams says our simian cousins are truly ambedextrous, but in man there is no such thing as real ambidexterity. Speech is man’s most salient characteristic, and it is possible that his dextrality is associated with this biologically peculiar development. Speech is represented on the left side of the brain. The muscular movements on Die right side of the body are dependent upon centres on the left side of the brain. This association between speech and right-sided muscular power is shown in the case of a “ fit of apoplexy.” When the haemorrhage is into the right brain there is paralysis of the muscles on the left side of the body, but no loss of speech. Another reason for dextrality is that man soon learned the left side of his body was more vulnerable than his right. He did not know that his heart was on the left side, but experience taught him that peneterating wounds of the left chest were more instantly fatal than similar wounds on the right chest, so he carried his shield in his left hand and wielded his weapon with his right. This greater activity of the right arm muscles would mean a correspondingly greater development of the left brain centres, so that, ultimately, not only the muscles of the right arm, but all the muscles on the right side of the body, would become stronger than those on the left side. '

A large number of left-handed people are afflicted in various degrees with stammering or other defects of that kind. The number is so large that the association cannot be fortuitous. This would suggest that, when the speech centre is situated in the right brain instead of in the left brain, it fails to reach the normal degree of development. A great many theories have been advanced in explanation of right-handedness, some of which are very far-fetched. Inasmuch as there is no anatomical -eason why people should favour the right hand, the practice has been confidently ascribed to the imitation of a habit begun by chance and aimlessly continued.) Some authorities have advanced the idea that right-handedness is due to the position of the infant in arms; by which one hand is restrained and the other allowed to develop. There are certain crafts, notably that of the surgeon, in which some approach to ambidexterity is an outstanding adJi said that the really expert pickpocket is always ambidextrous. Sir James Crichton-Browne deprecates the attempt to educate people mto ambidexterity. He says: “We cannot, I behove, get rid of our right-handedness, try how we may. Ambidextral culture, useful enough in respect of some few special movements in some few specially employed persons, must, on the larmj scale, tend to confusion.”